MDPE pipe diameter

B and Q were the cheapest when I bought a roll last Spring.
20mm is plenty if braces are used. Make sure you don't underestimate the length of the loops you need. Easily done.

Thanks beesrus, I'm working out the eventual height of what I want to cover. Soon realised I need more than I thought!

I used metal pipe clips and roofing batten on the chicken wire version and cable ties and bamboo on the mini version with the debris netting - last year all my hoops were connected to the bamboo with cable ties cheap as chips off ebay.